1. Field of the Invention
The present invention relates to an organic light emitting device, and more particularly, to encapsulating an organic light emitting device.
2. Discussion of the Related Technology
Organic light emitting devices deteriorate when water vapor and/or oxygen permeate thereto. Accordingly, there is a need to encapsulate organic light emitting devices to attain a stable operation and a long lifetime. For example, generally, metal cans or glass having grooves are prepared in a cap-like form. Then, water vapor absorption materials that are used to absorb water vapor are placed in the grooves in powder. Alternatively, water vapor absorption materials are formed into films and then adhered to the grooves using dual adhesive tapes.
Japanese patent Laid-open publication No. hei 9-148066 discloses an organoelectric light emitting display device, wherein an organic emission layer is interposed between a pair of electrodes facing each other, and such a stacked structure is encapsulated from an external environment by an airtight container containing a drying agent, such as alkali metal oxide or alkali earth metal oxide. However, the organoelectric light emitting display device is bulky due to the shape of the airtight container. In addition, even when the drying agent absorbs water vapor and retains its solid state, the drying agent becomes opaque. Therefore, the organoelectric light emitting display device cannot be used as a front emission type light emitting device.
U.S. Pat. No. 6,226,890 discloses an organoelectric light emitting device including a water vapor absorption material layer formed using a water vapor absorption material and a binder, wherein the water vapor absorption material includes solid particles having an average particle size of 0.1 to 200 μm.